Passage 1: Rabbits, Stoats, and Kiwis: The Ecology of New Zealand (2016)

The island nation of New Zealand is unique. Many of its animals and plants are found nowhere else. The kiwi is one of the most famous of these animals. This small, flightless bird dwells on the ground. It has tiny wings with which it is unable to fly. Kiwis belong to the same biological family as ostriches and emus, but they are much smaller than their relatives. Kiwis have round bodies and long beaks, and their brown feathers are very long and thin. Because of this, at first glance, someone who has never seen a kiwi before might think it has fur!

New Zealand is particularly fond of the kiwi. It is the country’s national bird. New Zealanders are even sometimes referred to as “kiwis.” Unfortunately, the kiwi is in danger due to changes humans made to New Zealand’s environment.

Hundreds of years ago, European colonists decided to bring rabbits from Europe to New Zealand. They wanted to hunt them for food and for sport. Unfortunately, their plan succeeded too well. In Europe, other animals in the food chain eat rabbits. This keeps their population in check. In New Zealand, though, no animals ate rabbits. So, their population grew to an enormous size. There were way too many rabbits!

The colonists tried to fix the problem by bringing another animal to New Zealand. Since none of New Zealand’s animals ate rabbits, the colonists imported one from Europe that did: the stoat. Stoats are small, carnivorous mammals similar to weasels. They eat rabbits, as well as birds and their eggs. Bird scientists warned the colonists to reconsider their plan, but the plan went forward—to the kiwi’s detriment.

New Zealand’s islands historically lacked predatory mammals. Because of this, kiwis’ flightlessness never put them at a huge risk of being hunted and eaten. This was the case until the stoats were released. The stoats began to eat the kiwis and their eggs in huge numbers. The kiwis had no way of protecting themselves from the stoats. As a result, their population plummeted.

To this day, stoats threaten the kiwi population in New Zealand. To protect native wildlife, residents have to tried to use various methods of trapping and hunting to limit the size of the stoat population. Certain areas have also been fenced in to keep stoats away from native birds like the kiwi.

To function, environments maintain a careful equilibrium between predators and prey. Altering this balance purposely or accidentally can have serious consequences.

Which of the following best summarizes the passage’s message?

Possible Answers:

Human interference in New Zealand’s environment has caused problems and harmed the kiwi, a native bird.

Kiwis are bound to be driven to extinction eventually.

By bringing rabbits to New Zealand, European colonists altered the natural balance of the environment.

Humans have caused a lot of problems in New Zealand.

Interfering in any environment is always a bad idea, no matter how good of an idea it might seem.

Correct answer:

Human interference in New Zealand’s environment has caused problems and harmed the kiwi, a native bird.

Explanation:

A good summary of a passage is not too broad or too specific. A summary that is too broad could encompass and describe a much wider range of topics than the passage actually discusses. A summary that is too specific will only relate to one of the passage's points. A good test to use is to consider whether the summary describes something relevant to each and every paragraph in the passage. If certain paragraphs don't relate to the summary at all, but others do, the summary is likely too specific to be the best one.

One way to approach a summary question is to consider how you would describe the passage to a friend who asked you what you just read. For this passage, you might say that it was about New Zealand, the kiwi, and the effects that humans bringing rabbits and stoats to the island have had. Notice that you wouldn't necessarily mention that New Zealanders are now trapping and hunting stoats using various methods—that's a detail that only pertains to one paragraph and likely wouldn't be included in a summary of the entire passage. Imagining you're describing the passage to a friend in a sentence or two can help you avoid including unnecessary detail.

Let's now look at the answer choices. "Kiwis are bound to be driven to extinction eventually" doesn't match the point of the passage. While the author discusses how stoats have reduced the kiwi's population, at no point does the author claim that the birds will necessarily be driven to extinction. "Humans have caused a lot of problems in New Zealand" and "Interfering in any environment is a bad idea, no matter how good of an idea it might seem" are both too general to be the best answer. Humans may have caused non-environmental problems in New Zealand, too, and it's possible that interfering in an environment in some way could be a good thing. We would at least need to see more evidence than the one narrative the passage provides to conclude that it's always a bad idea. The answer choice "By bringing rabbits to New Zealand, European colonists altered the natural balance of the environment" doesn't pass the paragraph test described earlier. The statement certainly describes the paragraphs that talk about the importation of rabbits, but what about the other paragraphs that talk about the stoats and kiwis? It doesn't reflect the point of those.

The best answer choice is "Human interference in New Zealand’s environment has caused problems and harmed the kiwi, a native bird." The focus on the kiwi specifically is appropriate, because before we hear about the environmental problems the European colonists caused in New Zealand, we learn about the kiwi. This is the best answer.

Groups of different animals affect one another in the natural world. For example, imagine that wolves and deer live in an area. A certain number of wolves need to eat a certain number of deer to survive. This keeps the population of the deer from getting too big. Similarly, the deer eat grass and vegetation. If there were more deer, they’d need to eat more grass.

The natural world is full of balances like these. Unfortunately, sometimes these balances are upset by invasive species. An invasive species is an animal or plant that has moved or been moved from its original environment to a new one. It has established a stable population there that is causing problems. Invasive species don’t cause problems in their original environments because they are kept in check by other plants and animals. In new environments, though, they have nothing stopping them from taking over.

One example of an invasive species is the zebra mussel. This animal originally only lived near Russia. Zebra mussels got into the Great Lakes by attaching themselves to the bottoms of ships. They now live in the Great Lakes too, where they upset the ecosystem. Zebra mussels eat algae, but so do fish. Many fish die as a result of there not being enough algae for all the animals to eat.

Plants can be invasive species too. Another example of an invasive species is the kudzu vine. Humans introduced the plant to the United States on purpose. Farmers were encouraged to grow it to protect their soil. Since then, it has gotten out of control. It now covers large parts of the South, outcompeting native plants for resources like water and sunlight.

Invasive species can cause environmental problems that are very difficult to fix. Because of this, it’s important to rethink introducing any species to a new environment. It’s also important to check to make sure when traveling that you are not bringing any plants or animals with you!

Which of the following excerpts from the passage best states its main idea?

Possible Answers:

"Invasive species don’t cause problems in their original environments because they are kept in check by other plants and animals."

"Plants can be invasive species too."

"Groups of different animals affect one another in the natural world."

"One example of an invasive species is the zebra mussel."

"Invasive species can cause environmental problems that are very difficult to fix."

Correct answer:

"Invasive species can cause environmental problems that are very difficult to fix."

Explanation:

To state the main idea of the passage, the correct answer is going to have to be not too general and not too specific. If it seems like a statement could describe a number of other things besides the topics the passage discusses, it's probably not a good main idea statement for that passage. On the other hand, if the statement only focuses on details that are only mentioned in a few paragraphs of the passage, it is also likely not a good main idea statement for that passage.

Let's skim over the passage and summarize what it discusses in each paragraph in a phrase or short sentence. Doing this can help us be more efficient when we consider the answer choices, as it will make it easier to spot any that are too general or too narrowly focused.

Paragraph 1: General introduction about how species affect one another in environments

Paragraph 2: Introduction and definition of invasive species

Paragraph 3: Example of invasive animal species (Zebra mussel)

Paragraph 4: Example of invasive plant species (Kudzu vine)

Paragraph 5: Summary and recommendations

Now, let's look at the answer choices.

"Groups of different animals affect one another in the natural world." - This answer choice is too broad. Animals affect one another in the natural world in a wide variety of different ways, but this passage talks about one specific way in which species can interact as a result of invasive species. This isn't a good expression of the passage's main idea.

"Plants can be invasive species too." - This answer choice is far too specific. The passage talks about invasive species and then mentions invasive plants as an example, so this isn't a good expression of the main idea of the passage.

"One example of an invasive species is the zebra mussel." - This answer choice is way too specific as well. The zebra mussel serves as an example of the passage's main topic, invasive species, so a statement about the zebra mussel being an example doesn't express the main idea of the passage very well.

The remaining two answer choices both have to do with invasive species:

"Invasive species don’t cause problems in their original environments because they are kept in check by other plants and animals." - This answer choice focuses on how invasive species don't have a negative influence on their original environments. The passage focuses more on the effects of invasive species after they have "invaded" a new area, not on how they fit into their original environments.

"Invasive species can cause environmental problems that are very difficult to fix." - This answer choice is correct. It focuses on how invasive species can cause problems in environments. This is what the passage focuses on, so this sentence is the best expression of its main idea.

All Common Core: 5th Grade English Language Arts Resources

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